1. Field of the Invention
The present invention relates to the field of systems for directing radiant energy and, more specifically, to the field of apparatus for correcting astigmatism, isofocal bias and ellipticity in a laser optic system which directs a beam at a workpiece.
2. Prior Art
The preferred embodiment of the present invention is designed to correct problems of astigmatism, isofocal bias and ellipticity in a pattern generation apparatus such as the pattern generation system commercialized by Ateq Corporation of Beaverton, Oregon, the assignee of the present invention, under the trademark CORE-2000.
The CORE-2000 pattern generation apparatus has been described, as the preferred embodiment, in a number of the United States patent applications including copending applications Ser. No. 178,868, now U.S. Pat. No. 4,796,038 entitled "A Laser Pattern Generation Apparatus", filed Mar. 28, 1988, assigned to the assignee of the present invention, which is a continuation of application Ser. No. 867,205, entitled "Laser Pattern Generation Apparatus", filed May 27, 1986, also assigned to the assignee of the present invention, now abandoned, which is a continuation of application Ser. No. 758,344, entitled "Laser Pattern Generation Apparatus", filed July 24, 1985, also assigned to the assignee of the present invention, now abandoned, and in copending application Ser. No. 784,856, entitled "Rasterizer For Pattern Generator", filed Oct. 4, 1985, and assigned to the assignee of the present invention.
The CORE-2000 pattern generation system and the above-mentioned patent applications are the most pertinent prior art known to the Applicant.
In addition, the Applicant is aware of U.S. Pat. No. 4,318,594 Hanada which describes a beam shaping optical system for treating diverging beams emitted from a semiconductor laser, U.S. Pat. No. 4,203,652 Hanada also for treating diverging beams emitted from a semiconductor laser, U.S. Pat. No. 3,974,507 Chemelli, et al. which describes an adjustable compact array of optical components which are relatively insensitive to beam steering and filamentation affects of the laser. Chemelli, et al. discloses that the optical output beam of the disclosed laser exhibits astigmatism and an elliptical cross section. Further, the Applicant is aware of U.S. Pat. No. 3,396,344 Broom which describes a semiconductor laser structure comprising a solid state laser formed by a block of semiconductor material containing a P-N junction layer having two opposite AND faces optically polished flat and parallel to one another as resonator reflectors, one of said AND faces being a radiation emitting surface when the laser is excited, in combination with a described collimating lens and a plano-cylindrical lens.
It is an object of the present invention to develop methods and apparatus for correcting problems of astigmatism, isofocal bias and ellipticity in a pattern generation apparatus.